The present invention relates to a high-frequency heating device such as microwave oven, for example.
FIG. 1 shows a conventional high-frequency heating device wherein a magnetron (or high-frequency oscillator) 3 is arranged above a heating chamber 2 housed in a body 1 and a turntable 4 is arranged in the heating chamber 2. The turntable 4 rotates in such a way that food 5 or the like mounted on the turntable 4 can be uniformly heated however high-frequency energy emanated from the magnetron 3 may be distributed in the heating chamber 2.
However, with this prior art high-frequency heating device shown in FIG. 1, the circular turntable 4 is arranged in the box-shaped heating chamber 2 so that each corner of heating chamber 2 and its adjacent portion are left unused, thus making it impossible to efficiently use the inside of heating chamber 2. When the space in which food 5 or the like is practically housed and which will be hereinafter referred to as cooking space is kept to have a certain volume, the dimension of whole heating chamber 2 itself becomes bulky, thus making it difficult to make the whole of device small-sized. In addition, the arrangement of mounting food 5 or the like on the turntable 4 needs a large-sized driving motor 6 having comparatively large output to drive the turntable 4. This is another reason why the prior art device could not be improved in cost and size.
FIG. 2 shows another conventional high-frequency heating device wherein a heating chamber 2 and a magnetron (or high-frequency oscillator) 7 are housed in a body 1 and high-frequency energy emanated from the magnetron 7 is introduced into the heating chamber 2 through a waveguide 8 and an exciting opening 8a formed in the roof of heating chamber 2 while stirred by a stirrer fan 10 attached to the roof of heating chamber 2 so as to make the distribution of high-frequency energy good in the heating chamber 2. A partition plate 9 is provided for covering the stirrer fan 10 from below and being made of dielectric material having low dielectric loss (tan .delta.).
With the prior art device shown in FIG. 2, the stirrer fan 10 arranged in the heating chamber 2 makes it necessary to form in the heating chamber 2 a comparatively large space in which the stirrer fan 10 is housed. In addition, the height of partition plate 9 must be made comparatively large. Therefore, when the cooking space in the heating chamber 2 is kept to have a certain volume, the whole of heating chamber 2 can not avoid being made comparatively bulky, which was a problem standing on the way of making the whole of device small-sized.